Control mechanism for grinding machines



Aug. 3, 1937. P. PLANTINGA CONTROL MECHANISM FOR GRINDING MACHINES Filed May 20, 1935 2 Sheets-Sheet 1 Aug. 3, 1937. P. PLANTINGA CONTROL MECHANISM FOR GRINDING MACHINES Filed May 20, 1955 2 Sheets-Sheet 2 WIQ,

r zn a R! TM Patented Aug. 3, 1937 UNHT'ED STATES CONTROL MECHANISM FOR GRINDING MACHINES Peter Plantinga, Amherst, Mass, assignor to Greenfield Tap & Die Corporation, Greenfield, Mass, a corporation of Massachusetts Application May 20, 1935, Serial No. 22,303

Claims.

This invention relates to control mechanism for a grinding machine and relates more particularly to improvements in the control mechanism shown in my prior Patent No. 1,873,151, is-

5 sued August 23, 1932.

i In said prior patent I disclosed means for controlling the cross feed of a grinding machine duringthe grinding operation and for gradually decreasing the rate of feed. I also provided means to stop the feed and to withdraw the wheel for a wheel-truing operation before the finish grinding, together with means for automatically effectingthefinish grinding and for stopping the feeda second time at the end of the finish grinding operation.

It is sometimes found-desirable to stop the cross feed before actual completion of the total grinding cycle and more particularly at the end of the rough grinding operation, and in such a Way that it will not require the attention of the operator. 4

It is the general object of myinvention to provide auxiliary means for thus automatically stopping the feed at any selected point before or at :2 the completion of the rough grinding operation and without changing-the setting of the auto-- 1 maticcontrol mechanism. I

I also provide a construction by which said automatic disabling means may be rendered inoperative when desired.

l My invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in .the appended claims.

A preferred form. of the invention is shown in the drawings, in which Fig. 1 is a partial front elevation of the cross feeding mechanismof a grinding machine;

Fig. 2 is a sectional side elevation,taken along 40 the line 2- -2 in Fig. 1;

Fig. 3 is a detail side elevation, looking in the direction of the arrow 3 in Fig. 1;

Fig. 4 is a plan view, looking in the direction of the arrow 4 in Fig. 1,;

Fig. 5 is a front elevation of certain parts, as indicated by the line 5 '5 in Fig. 4;

Fig. 6 is an enlarged front elevation of certain parts shown in Fig. 1, and

Fig. 7 is a sectional side elevation, taken along .50 the line l-l in Fig. 4.

My improvements are particularly adapted for use on a grinding machine of the type in. which the grinding wheel is mounted for transverse or cross feeding adjustment radially of the work,

55 and in which thework is mounted for reciprocating v axial movement relative to the grinding wheel.

I will first describe briefly the mechanism shown in my prior patent for feeding the grinding wheel transversely toward or from the revolving work. Referring particularly to Figs. 1 and 2, a cross feed shaft is mounted at its outer end in a fixed bearing 3| and is provided with a disc 32 fixed to said shaft and having a ratchet wheel 33 and ring gear 34 mounted thereon. The shaft 30 is effective to move the wheel slide through any usual operating connections or. gearing not shown.- An outer flange 35 of the disc 32 also forms gear engaged by a pinion 36 mounted in a hand wheel 31 and normally held from relative rotation therein. The pinion 36 may be turned manually in its bearing in the hand wheel when relative adjustment ofthe hand wheel and disc 32 is desired. A cam ring 40is mounted on the disc 32 and is moved angularly therewith.

A feed pawl 4! (Figs. 1 and 2) is fixed to a stud 43 pivoted in a pawl carrier 44 slidable on parallel rods. 45. A second pawl 42 is loose on the stud 43. Aspring 46 (Fig. l) is connected to J a stud 41 (Fig. 4) fixed in the pawl 4| and projecting loosely into an enlarged opening in the pawl 42. The spring 46 has a rearwardly projecting end 48 engaging the back edge of the pawl 42.

The pawls areso arranged that the point of one pawl is a half-tooth to the rear of the point of the other pawl, so that a half tooth feed can be taken if desired. The carrier 44 is forced rearward or to the right in Figs. 1 and 4 by a coil spring 5!] (Fig. 4).

An upwardly projecting arm 52 (Figs. 1 and 4) is formed as part of a bell crank 53 mounted on a pivot stud 54. The arm 52 engages the rear end of the pawl carrier 44 and the laterally projecting arm of the bell crank 53 is provided with a cam roll 55 engaging the cam ring 40 previously described. The cam is provided with steps or concentric portions at different distances from its axis, as clearly shown in Fig. 1, and the greater the radius of the cam step, the smaller return or non-feeding movement of the pawl carrier 44 will take. place.

The limit of advance movement of the carrier is fixed and consequently the rate of cross feed is determined by the stepson the cam 40. Each cross feeding movement at the beginning of the grinding operation is fairly large, but the extent of movement is progressively decreased as the grinding approaches finish size.

The mechanism for giving the pawl carriage or carrier 44 its feeding movement comprisesa rocker 51 (Fig. 5) loosely mounted on the pivot stud 54 previously described and provided with an adjustable contact screw 60 adapted to engage the rear face of the upwardly extending arm 52 of the bell crank 53. A portion 6I of the rocker 51 is positioned above a stud 62 adjustably secured in the upper end of a piston rod 63 connected to an actuating piston in a hydraulic cylinder 65. Pressure is admitted below said piston at the limit of work travel, and at each feeding operation the piston moves the rod upward until the piston engages a fixed stop.

During the normal operation of the machine, the feed pawls are thus actuated hydraulically by mechanism controlled by the work table, but the extent of each feeding movement is controlled by the cam ring 40.

When the cross feed is to be automatically reversed to withdraw the wheel from the work,.it is necessary to first disengage the feed pawls. For this purpose I provide a release lever I50 (Figs. 1 and 4) fixed to the stud 43 to which the feed pawl M is also secured and on which the feed pawl 42 is loosely mounted.

The outer end of the lever I50 is provided with an extended surface I5I (Fig. 4) underlying an arm I52 fixed to the end of a rod I 53slidably mounted in a fixed bearing I54 (Fig. 1). An arm I55 is fixed to the opposite end of the rod I53 and is provided with a cam roll I56 positioned to engage a cam I51. The cam I51 is formed with three equally spaced raised portions I51, one of which is indicated in Fig. 3.

When the cam roll I56 engages one of the depressed portions of the cam I51, the arm I52 is raised by a spring I 64 (Fig. 1) and the feed pawls 4I 'and 42 are free to engage the ratchet'wheel 33.

When the roll I56 is raised by one of the high parts I51 of the cam I51, the arm I52 is depressed and the feed pawls are raised out of engagement with theratchet wheel 33.

As previously stated, it is desirable on occasion to discontinue the cross feed, independently of the action of the regular control mechanism. For this purpose I have provided the release lever I50 with an arm I60 (Figs. 4 and 6) having a cam portion I6I formed at the outer end thereof.

I also provide a spring plunger I62 (Fig. 7) mounted in a recessed portion I63. of a plate I64 which may be secured to the face of the cam 40 by clamping screws I65.

The cam 40 is. preferably provided with segmental recesses I66 and segmental slots I61 permitting limited circumferential adjustment of the plate I64. An adjusting screw I10 loosely rotatable in a projection I1I on the cam 40 is threaded into a swiveled memberi12 mounted in the plate I64 and. constitutes means for closely adjusting the.plate.I64 and plunger I62 to a desired position.

The plunger I62 is forced outward by-a spring I13-and its outward position is determined by a stop pin I15, normally-seated in the end of slots I16 (Fig. 4) in a hub portionI11 through which the plunger slides. A knob I18 is provided for drawing the plunger,I62 forward when desired.

If it is desired to stop the cross feed of the grinding machine before the regular control cam I51 acts, the plate I64 is secured on the cam 40 in such a position that the plunger I62 will engage the Cam-shaped end I6l of the arm I60 and will move the arm I 60 upward, thereby lifting the feed pawls 4| and 42 out of engagement with the ratchet wheel 33.

When it is thereafter desired to again start the automatic feed, the operator merely withdraws the plunger I62 by grasping the knob I 18 and pulling the same forward. This allows the arm I60 to drop and release the feed pawls, whereupon automatic feeding is resumed.

If it is desired to render the auxiliary stopping device inoperative, the operator pulls the plunger forward by the knob I18 until the stop pin I is out of the slots I16, after which he turns the knob and plunger 90 and seats the stop pin in the shallow notches I80 (Fig. 7). When the parts are in this position, the plunger I62 is withdrawn to inoperative position with respect to the arm I60.

With this device, the cross feed may be stopped at any desired point prior to the completion of a grinding operation as determined by the regular control mechanism, and the exact point at which the cross feed is stopped can be determined and adjusted by the circumferential setting of the plate I64.

This auxiliary device is found to be of great utility when it is for any reason desirable to operate the grinding machine serni-automatically and to provide for the interruption of a grinding operation without the personal supervision of the operator.

It will be particularly noted that the setting of the regular control device remains unchanged and that said device is in full and regular control whenever the auxiliary device is rendered inoperative.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claim is:

1. In a grinding machine having a grinding 1 wheel and a cross feed mechanism therefor, in combination, means to stop the cross feed after a predetermined grinding period, and auxiliary means to interrupt said cross feed at a selected and earlier time in said grinding operation, said auxiliary means. comprising a release member, a device to engage and actuate said member, and means to free said member from said device after the cross feed is stopped thereby.

2. In a grinding machine having a grinding wheel and a cross feed mechanism therefor, in combination, means to stop the cross feed after a predetermined grinding period,. and auxiliary means to interrupt said cross feed at a. selected and earlier time in said grinding operation, said auxiliary means comprising a release member, a device rotating adjacent thereto, a spring plunger mounted on said rotating device, and selective means to hold said plunger in operative or inoperative position. with respect tosaid release member.

3. In a grinding machine having a grinding wheel and a cross feed mechanism therefor, in combination, means to stop the cross feed after a predetermined grinding period, auxiliary automatic means to render said cross feed inoperative at an earlier predetermined point in the grinding operation, the set-up of the cross feed mechanism and of the stopping means remaining unchanged, and manual means to render said cross feed mechanism again operative at the identical point in the cross feed operation at which the cross feed was automatically interrupted.

4. In a grinding machine having a grinding wheel and a cross feed mechanism therefor, in combination, actuating devices for said cross feed mechanism, means to stop the cross feed after a predetermined grinding period, means to disengage said actuating devices at an earlier predetermined point in the grinding operation, and manual means to efiect reengagement of said actuating devices at the identical point in the cross feed operation at which the cross feed 10 Was interrupted.

wheel and a cross feed mechanism therefor, in combination, actuating devices for said cross feed mechanism, means to stop the cross feed after a predetermined grinding period, means to disengage said actuating devices at an earlier predetermined point in the grinding operation, and manually operable means to Withdraw and hold said disengaging means in inoperative position to permit continued operation of said cross feed mechanism.

PETER PLAN'IINGA. 

